Glyceride crystallization process



3,059,011 GLYCERIDE CRYSTALLIZATION PROCESS Fredric J. Baur, Cincinnati, Ohio, assignor to The Procter 8: Gamble Company, Cincinnati, Ohio, a corporation of Ohio No Drawing. Filed Dec. 6, 1961, Ser. No. 157,558 9 Claims. (Cl. 260428) This invention relates to an improved crystallization process. More particularly, it relates to the addition of certain crystal modifying agents to glyceride oils containing fatty materials which are insoluble in the oils, whereby separation of the insoluble fatty materials from the oils is facilitated.

A large amount of vegetable glyceride oil is used as salad oil. Such oils can serve as a base for various liquid salad dressings, providing an oily coating for salad ingredients. They are also used in mayonnaise emulsions. Both salad oils and mayonnaise are usually kept under refrigeration by the housewife. At temperatures of about 40 F. or lower, fatty materials will deposit out of many salad oils, causing them to have a cloudy appearance. In mayonnaise, such crystal formation tends to break the emulsion, causing separation of fatty material from the aqueous portion.

If soybean oil is used as a salad oil it tends to develop a characteristic beany odor and flavor. Even when it has been rendered completely odorless and flavorless by high-temperature steam deodorization, the characteristic odor and flavor will return, in part, at least, due to the linolenic acid content of the oil.

It has been proposed that the stability of soybean oil against odor and flavor reversion can be increased by hydrogenation. However, hydrogenation decreases the unsaturation of unsaturated component fatty acids and also converts the unsaturated acids to higher-melting and less soluble isomers. The oil must then be winterized by a process including cooling and subsequent separation of insoluble glycerides to remove materials which will solidify when the oil is refrigerated, and thereby cause undesirable salad oil performance and appearance. Other oils such as cottonseed oil are given a similar Winterizing treatment. Insoluble fatty materials in oils such as corn oil are also removed by a cooling step, followed by a separation step.

Another important use of glyceride oils is in the paint industry. Oils of particular interest are the so-called drying oils which form protective coatings because of the ability of these oils to polymerize or dry after they have been applied, thereby forming tough, adherent, impervious and abrasion-resistant films.

It is generally believed that the film-forming properties of drying oils are related to their degree of unsaturation, and that the films are formed by polymerization of double bonds present in unsaturated oils. It is highly desirable, therefore, that oils suitable for use as drying oils contain a large amount of triunsaturated glycerides, and relatively few trisaturated glycerides or mixed saturated-unsaturated triglycerides.

U.S. Patents 2,442,531 and 2,442,533, issued to E. W. Eckey on June 1, 1948, disclose the directed rearrangement of triglycerides. By means of the process disclosed in these patents a substantial portion of the mixed saturated-unsaturated triglycerides is rearranged to form a larger proportion of highly saturated glycerides and highly unsaturated glycerides. The more saturated glycerides in crystalline form are then separated from the rearranged mixture, leaving an unsaturated oil very suitable for use as a drying oil.

Special coating fats are required for coating of candies.

Q UCQ These fats must have a high melting point so that they will not be greasy at normal room temperatures. However, these fats must also melt in the mouth when the candy is eaten, and thus the presence of fats melting at too high temperatures is undesirable. When oils such as hydrogenated palm kernel oil, and palm oil, either hydrogenated or unhydrogenated, are to be used for this purpose, it may be desirable to separate out highly-saturated materials which would produce a waxy taste in the mouth. Suitable confectioners fats can also be formed from the more saturated portions of directed rearranged triglycerides.

At times it is desirable to use palm oil as a major constituent of a margarine oil. In certain geographic locations palm oil is cheaper than other oils, and a supply of palm oil may be more readily available than a supply of some other oil. It has been found that the content of high-melting insoluble fats in palm oil, at a temperature of 92 F., is too high to produce a satisfactory margarine, since these insoluble fats will impart a waxy taste in the month during eating. Separation of the insoluble fats from the palm oil increases its utility as a margarine constituent.

One of the main problems encountered in the separation of insoluble fatty materials from glyceride oils has been the fact that the insoluble fatty materials entrain a large amount of glyceride oil. In addition, conventional separation procedures are very slow.

It has now been found that by the process of this invention the separation of insoluble fatty materials from liquid glyceride oils is greatly facilitated, thereby permitting the recovery of a much larger amount of liquid oil than has heretofore been possible. In addition, the rate of separation is greatly increased. As used herein the term insoluble fatty materials is intended to include materials which dissolve in oils at elevated temperatures and which will precipitate out of solution as the oils are cooled and allowed to stand.

It is therefore an object of this invention to provide a process for modifying insoluble fatty materials in glyceride oils whereby the subsequent separation of the fatty materials is greatly facilitated.

It is a further object of this invention to provide an improved process for making a salad oil.

Another object is to provide an improved method of making a drying oil.

Yet another object is to provide a method of making confectioners fats which have good eating quality.

Other objects and advantageous features will be apparent from the following detailed description.

In general, the process of this invention comprises the steps of dissolving in a glyceride oil containing insoluble fatty material, at a temperature at which substantially all of said fatty material is in solution in said glyceride oil, from about 0.001% to 1.0%, by weight of oil, of fatty acid ester of gluclose or a glucose derivative such as gluconic acid, or glucono-delta lactone, cooling said oil so that saturated glyceride crystals will form, and separating an uncrystallized portion of said oil from said crystals. Esters suitable for the practice of this invention contain, per molecule, at least one saturated long-chain fatty acid having from 14 to 22 carbon atoms. Preferred esters are those in which the fatty acid is selected from the group consisting of palmitic and stearic acids.

The esters exert a modifying effect on the insoluble material so that it comes out of solution in the form of large crystalline aggregates. These entrain a smaller amount of liquid fatty glycerides during separation than do crystals formed in the absence of ester.

The process of this invention is generally applicable to any glyceride oils which contain fatty materials which will dissolve in the oils at elevated temperatures and which will crystallize out of solution when the oils are subsequently cooled and allowed to stand. For example,

the removal of insoluble fatty materials from oils which 7 carried out as decribed in U.S. Patent 2,442,531, issued.

June 1, 1948, in which triglyceride oils are contacted with a low-temperature molecular rearrangement catalyst at such a temperature that the more highly saturated triglycerides are precipitated as they are formed during the rearrangement of the glycerides in the oil. A list of suitable rearrangement catalysts is set forth in the aforementioned U.S. Patent 2,442,531. However, it is to be understood that other suitable rearrangement catalysts and operating condition can be used. As used herein the term directed rearrangement is intended to denote a molecular rearrangement process directed for a greater yield of highly saturated and highly unsaturated glycerides than would be found in an oil having a random distribution of fatty acid triglycerides.

As has been heretofore stated, esters suitable for use in the process of this invention include esters of glucose and saturated fatty acids containing from 14 to 22 carbon atoms. Other suitable esters include corresponding fatty acid esters of gluconic acid which can be made by mild oxidation of the glucose. Removal of water from gluconic acid will result in the formation of glucono delta lactone, and the saturated fatty esters of this compound are also suitable for use in this invention.

While single fatty acids, such as palmitic acid, may be used for esterification, it is not essential that pure or single acids be used. Therefore, the present invention contemplates not only the esters of single saturated fatty acids having from 14 to 22 carbon atoms, but also mixtures of two or more .of such acids.

Esters ofglucose and glucose derivatives can be prepared by reaction of the glucose or derivatives, in the presence of a suitable catalyst, with an anhydride of a saturated long chain fatty acid. Other methods, such as reaction of glucose or derivative with acid chlorides are also suitable, and it is to be understood that the invention is not limited to any particular method of preparation of the ester.

It is preferred that the oils to be processed be heated to a temperature at which substantially all of the insoluble fatty; material is in liquid form prior to slowly cooling the oil in which is dissolved the glucose ester. The ester can be added prior to or after heating. The exact conditions for cooling will vary with the amount of oil in the batch and the amount of insoluble fatty material, but the optimum cooling conditions can be determined by those skilled in conventional oil graining procedure.

The insoluble fatty materials are conveniently separated by conventional filtration procedures, but other methods of. separation such as centrifuging, can be used.

The improved results which can be achieved by the process of this invention are clearly illustrated by the following examples:

EXAMPLE I The following glucose esters were prepared by the indicated methods:

A. Glucose Pentapalmitate A solution of 50 g. of palmitoyl chloride in 100 m1. of chloroform was slowly added, with vigorous stirring, to

a mixture of 6 g. of glucose, 26 ml. of pyridine, and 50 ml. of chloroform. Two liquid phases formed, and the mixture was allowed to stand overnight. The mixture was then poured onto crushed ice with vigorous stirring, and an emulsion formed. Most of the chloroform was stripped off from the mixture with an aspirator, and a layer of water was decanted. About 150 ml. of ethyl ether and ml. of ethyl alcohol were added to the wet precipitate, which dissolved upon heating. A water layer separated out and was drawn oif. The remaining material was cooled to about 20 C.., and filtered, and the solid material was dried in a desiccator. The dried product was glucose substantially completely esterified with palmitic acid.

B. Gluconic Acid Palmitate 18 g. of glucono delta lactone were dissolved in 100 ml. of dry pyridine while being heated over a steam bath. The solution was cooled to room temperature and placed in a flask equipped with a stirrer, dropping funnel, and reflux condenser. 84 g. of palmitoyl chloride were added dropwise to the stirred solution. The mixture was then heated on a steam bath with continuous stirring for 3 hours and allowed to stand overnight.

75 ml. concentrated NCl were mixed with ml. water, cooled to 0 C., and placed in a 4-liter separatory funnel with the reaction mixture. The mixture was then extracted 5 times with 400 ml. portions'of ethyl ether. The ether extracts were combined in a 4-liter separatory funnel and washed twice with 400 ml. portions of water to remove all traces of pyridine hydrochloride which had formed. The ether was then evaporated on a steam bath. The last traces of solvent were stripped off using high vacuum. The product was mainly a mixture of gluconic acid triand tetra-esters of palmitic acid.

C. Glucono Delta Lactone Monopalmitate 435.2 g. of pahnitic acid, 1105 g. phenol, and 250 m1. of toluene were refluxed in apparatus containing a moisture trap until dry. 302.6 g. of glucono delta lactone and 8 g. p-toluenesulfonic acid catalyst were added, and the mixture was refluxed at C. for about 1 /2 hours. A few ml. of pyridine were added and the solvents distilled off under vacuum. The pot temperature was raised to 65 C. and was then dropped to 120-130 C. The product was vacuum-steam deodorized at this temperature for 4 hours. The pot residue was taken up in ethyl ether, washed '3 times with 5% hydrochloric acid and 3 times with water. The ether was evaporated. The product was then decolorized in 200 g. lots, using 2000 m1. of hexane, 10 g. of a deodorizing charcoal and 10 g. of diatomaceous earth.

Two additional batches of material were made using the same procedure, and mixed together. The product was primarily glucono delta lactone monopalmitate.

1600 g. of refined and bleached soybean oil containing 0.5% of sodium methoxide as a rearrangement catalyst, were heated to 120 F. and maintained at that temperature for 35 minutes. The sodium methoxide was in the form of a suspension in xylene prepared by the gradual addition, during vigorous agitation, of anhydrous methanol to an equivalent quantity of finely dispersed sodium in xylene. The oil mixture was then cooled very slowly with stirring to 50 F. After 5 days storage at 50 F. the oil mixture was treated withacetic acid to destroy the rearrangement catalyst, 'water washed, and dried.

Testing samples were prepared by placing 100 g. of the rearranged oil in containers together with the abovelisted esters in the amountsindicated. The esters are identified by the corresponding letters. The samples were melted on a steam bath, and then allowed to cool slowly to 30 F. The samples were held at 30 F. for 48 hours and then filtered through a Buchner funnel until the rate of filtration decreased to 1 drop per 10 seconds. This 'was selected as representing substantial'completion of filtration. The filtration time to reach this point was 5 recorded, and the filter cakes were weighed. The following results were noted:

The iodine values of the filtrates were all substantially the same.

As can be seen from the above data, the addition of esters of glucose or glucose derivatives to the soybean oil resulted in a great decrease in filtration time. Also, the amount of entrained oil in the filter cake was reduced as shown by the comparison of weights of the filter cake.

A similar improvement in filtration can also be achieved by using esters of other fatty acids such as myristic, stearic, arachidic, and behenic acids. Also, esters of mixtures of these acids with each other or with palmitic acid can be substituted in the foregoing examples with comparable results. The use of from 0.001% to 1.0% of any of these esters will provide quicker and more effective separation of the solids from directed rearranged soybean oil.

EXAMPLE H Glucose pentapalmitate was dissolved in a one-pound sample of refined cottonseed oil at a level of 0.005% by weight. This oil, and also a sample of oil without glucose ester, were heated to a temperature of 140 F. with stirring. The samples were cooled gradually to 60 F. and held at that temperature for about 24 hours. They were then cooled slowly to a temperature of 45 F. and held at that temperature for about 24 hours until crystallization appeared to be substantially complete. Each sample was vacuum filtered using a Buchner funnel and filter paper. The filtration was continued until the filter cake developed cracks. The filtrates were weighed and the yield of oil was calculated. These data were as follows:

Amt. Additive (percent) Filtration Yield of Yield of Time Oil (g.) Oil l) (percent) None 487. 5 355 78. 5 0.005 40. 349 77. 9

As can be seen from the above, the filtration time was greatly decreased when the additive was present.

EXAMPLE HI Amt. Additive (percent) Filtration Yield of Time (min) Oil (g.)

Nrme l2. 320 n m 12. 0 320 EXAMPLE IV A mixture was formed of olive oil containing 5% of triglycerides containing an average of about 2 palmitic and 1 stearic acid groups per molecule. 0.2%, by weight of glucose pentapalmitate was added to the mixture, and

it was heated to temperature high enough to dissolve all solid material present. The mixture was then cooled to F. and held at that temperature for 2 days. A similar mixture which contained no additive was treated in the same manner. At the conclusion of the 2 day period the mixtures were compared. It was noted that the mixture containing the additive was separated into a clear oil layer, comprising 35% of the total volume, and a layer of precipitated crystalline material. The mixture without additive was in the form of a slurry and no clear oil layer was visible.

EXAMPLE V Samples were prepared similar to those of Example IV except that the additive was 0.2% of glucose partially esterified with an average of between 2 and 3. palmitic acid groups per molecule. After treatmentas specified in Example IV the mixture containing the additive sepa rated to provide a clear oil layer comprising 50% of the total volume.

EXAMPLE VI Soybean oil was hydrogenated to an iodine value of and winterized by holding it at 50 F. for 2 weeks, and then holding it at 40 F. for 3 days. The oil was then vacuum filtered. A mixture was formed containing 95% of the clear filtrate and 5% of a saturated triglyceride containing about 2 palmitic groups and 1 stearic group per molecule. This saturated triglyceride had an iodine value of 0.01. To the mixture was added 0.1%, by weight, of glucose pentapalmitate. 250 g. samples of the oil mixture, with and without added ester, were heated to F. for 1. hour to destroy all crystal nuclei, and then cooled to 80 F. and held at that temperature for 3 days to permit crystals to form. The resulting mixture of insoluble fatty material and glyceride oil was filtered through a Buchner funnel using filter paper and vacuum. The following measurements were recorded of the total amounts of oil passing through the filters at various time intervals:

1 Not measured.

Comparable results will be achieved by substitution in the foregoing examples of oils such as directed rearranged glyceride oils, hydrogenated glyceride oils, and other glyceride oils containing fatty materials insoluble in these oils at higher temperatures.

Although it is to be understood that the invention is not to be limited to any theory, it is believed that esters suitable for improving the filtration of oils for the purpose of separating insoluble fats from oils should contain a substrate-similar and a substrate-dissimilar moiety in the molecule. In the case of the aforementioned systems,

fatty acid chains in the fats and in the glucose ester are similar. The glucose portion of the additive represents a polyhydric compound which is dissimilar from that of the fats.

It is also believed that it is important that materials added as filtration aids bear some relation in melting point and/or solubility to the fats which are to be separated by filtration. These aids should be made with fatty acids having neither too high nor too low a melting point, so that the modifier will have a tendency to deposit on the incipient crystal nuclei as they are formed, thereby modifying the fat crystals. This results in the formation of crystal aggregates (around a crystallization center) which are compact and not feathery and are more easily filtered.

Further, it is believed that if the additive has too high a melting point or too low a solubility in the oil, nuclei of additive will tend to form before the fat nuclei are formed, and the additive may act as a nucleating agent for the fat, forming more nuclei than would normally appear in the fat. As a result the fat crystal aggregates will be more numerous and filtration will be more dif- Although specific examples have been given to illustrate the invention, his to be understood that the invention is not to be limited to these'examples, and that variations in the processing conditions which will suggest themselves to those skilled in the art are intended to be Within the scope of the invention. It will further be appreciated that the esters used in the practice of this invention usually will be a mixture of various esters and that the specified proportions of fatty acids represent average values for such mixtures.

This is a continuation-in-part of application Serial No. 45, filed January 4, 1960.

What is claimed is:

1. The method of separating insoluble fatty material from glyceride oil which comprises the steps of dissolving in said glyceride oil, at a temperature at which substanlong-chain fatty acid, having from 14 to 22 carbon atoms,

and material selected from the group consisting of glucose, gluconic acid, and glucono delta lactone, cooling the glyceride oil to a temperature at Which insoluble fatty material comes out of solution, and separating the insoluble fatty material from the oil.

2. The method according to claim 1 wherein the fatty acid is selected from the group consisting of palmitic and stearic acids.

3. The method according to claim 1 wherein the ester is glucose pentapalmitate.

4. The method according to claim 1 wherein the ester is a mixture of gluconic acid tripalmitate and gluconic acid tetrapalmitate.

5. The method according to claim 1 wherein the ester is glucono delta lactone monopalmitate.

6. The method according to claim '1 wherein the ester is composed of glucose and an average of between two and three palmitic acid groups.

7. The method according to claim 1 wherein the oil is cottonseed oil.

8. The method according to claim 1 wherein the oil is. hydrogenated soybean oil.

9. The method according to claim 1 wherein the oil is a directed rearranged glyceride oil.

No references cited.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N00 3,05%011 October 16 1962 Fredric J, Baur It is hereby certified that error appears in theabo've numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 3, line 24 for "condition" read conditions column 6 line 45, the first entry under the "Time, (min,)" column should be 1/2 Signed and sealed this 30th day of April 1963.,

(SEAL) Attest:

ERNEST w. SWIDER DAVID L. ADD

Attesting Officer Commissioner of Patents 

1. THE METHOD OF SEPARATING INSOLUBLE FATTY MATERIALL FROM GLYCERIDE OIL WHICH COMPRISES THE STEPS OF DISSOLVING IN SAID GLYCERIDE OIL, AT A TEMPERATURE AT WHICH SUBSTANTIALLY ALL OF SAID FATTY MATERIAL IS IN SOLUTION, FROM ABOUT 0.001% TO 1.0%, BY WEIGH OF OIL, OF ESTER OF SATURATED LONG-CHAIN FATTY ACID, HAVING FROM 14 TO 22 CARBON ATOMS, AND MATERIAL SELECTED FROM THE GROUP CONSISTING OF GLUCOSE, GLUCONIC ACID, AND GLUCONO DELTA LACTONE, COOLING THE GLYCERICE OIL TO A TEMPERATURE AT WHICH INSOLUBLE FATTY MATERIAL COMES OUT OF SOLUTION, AND SEPARATING THE INSOLUBLE FATTY MATERIAL FROM THE OIL. 